Strengthen your determination through physical and mental exercise.

Do aerobic exercises.
If you can push yourself to start, then the ever-increasing executive function that arises from your exercise will decide to engage in exercise ever easier, leading to a positive feedback cycle in your favor.

Do mindfulness meditation.
It teaches attention control, emotion regulation, and increased self-awareness.

Get proper sleep.
This will give you the energy you need.

Remember that determination is a way of life.